Conventional microscope objective lenses require large numbers of cemented lenses for favorably correcting various aberrations, in particular, chromatic aberration, and also require the use of anomalous dispersion glass materials for correcting secondary spectra. Accordingly, conventional microscope objective lenses are inevitably expensive. In recent years, high-magnification, large numerical aperture lens systems are being proposed which use a diffractive optical element (DOE) capable of correcting various aberrations, in particular, chromatic aberration including secondary spectra without having to use large numbers of cemented lenses and anomalous dispersion glass materials (for example, refer to Patent Document 1).
Patent Document 1: Japanese Patent Laid-Open No. H06-331898